In the field of automotive fuel systems, fuel tanks are made typically from a weldable polymeric material such as a high-density polyethylene (HDPE). A polymeric fuel tank is resistant to corrosion and can be efficiently manufactured, such as by blow molding, which permits flexibility in fuel tank design. Further, since the polymeric fuel tank is lightweight, the vehicle in which it is installed is more fuel efficient and economical to operate.
Relatively soft polymeric materials that lend themselves to efficient fuel tank manufacturing typically are not suitable for making quality fuel system components, such as vent valves. For instance, a vent valve made largely or entirely out of the same material as the fuel tank can be damaged using a conventional method such as hot plate welding to weld a port for the vent valve to the polymeric fuel tank. On the other hand, harder materials such as nylon with higher-melting temperatures suitable for use in the vent valve are difficult if not impossible to weld to the polymeric fuel tank. Nylon and HDPE, for example, simply do not weld together very well due to their different melting temperatures and other properties.
Various mounting assemblies have been proposed to overcome problems associated with mounting fuel system components, such as the nylon vent valve, in a wall of the polymeric fuel tank. However, due to the incompatibility of tank and fuel system component materials, interfaces continue to suffer from fuel vapor permeation problems permitting hydrocarbons to escape from the fuel tank.
Government regulations and environmental concerns will likely continue to require that fuel tanks and their components control hydrocarbon emissions. Therefore, a non-weldable vent valve structure is needed that can be efficiently produced and securely attached to a polymeric fuel tank to reduce fuel vapor permeation from the fuel tank.